This invention relates generally to ring laser gyroscopes (gyros) and particularly to a ring laser gyro configured to be less sensitive to magnetic effects than would otherwise be the case.
Ring laser gyros generally feature a base of a ceramic material having a low coefficient of thermal expansion and passageways within the base which, together with mirrors, form a closed optical cavity for counterpropagating beams of coherent light. The base forms a sealed envelope containing a suitable gas under a low pressure in the closed optical cavity. Electrodes (anodes and cathodes) are disposed in communication with the optical cavity so that an electrical potential sufficient to support plasma excitation and lasing is maintained in the gas. As is well known in the ring laser gyro art, the laser has a gain section which is that portion of the closed optical cavity in which the electrodes, when energized, maintain a discharge in the ionized gas or plasma.
Ring laser gyros are sensitive to magnetic effects which tends to reduce their accuracy and thus affects their usefulness in many applications such as, for example, north seeking systems. Prior to the present invention, various gyro configurations have been used to reduce these magnetic effects. One such configuration of which the applicants herein are aware is discussed in U.S. Pat. No. 4,705,398 issued on Nov. 10, 1987 to Lim, et al. More often, magnetic sensitivity is reduced by appropriate shielding against magnetic effects. Magnetic shielding requires additional components, is cumbersome, adds to the cost of the gyro, and is otherwise disadvantageous.